Re: Little design mistakes that can be easily avoided (2): Listenning to CELKO (and CELKO alikes)

On 27 mai, 14:58, "David Cressey" <cresse...@xxxxxxxxxxx> wrote:
"Matthias Klaey" <m...@xxxxxxxxxxx> wrote in message

news:5bsi53h8bt88nf7iaj0tpk6e3rbjkv9mh8@xxxxxxxxxx



Cimode <cim...@xxxxxxxxxxx> wrote:

On 27 mai, 05:16, paul c <toledobythe...@xxxxxxxx> wrote:
Matthias Klaey wrote:
Cimode <cim...@xxxxxxxxxxx> wrote:
...

Hmm. Is this just the usual Celko-bashing in this newsgroup? Did you
intend to write a parody on how to misread and misinterpert other
peoples texts? You don't mean this seriously, do you?

Usually I think much of what he writes here deserves to be bashed as it
is not about theory, just various flawed products, workarounds and
various design gospel he likes to preach. I think it's okay to talk
about that stuff in a product group but this is a theory group.
Agreed. When one wants to speak about *taxonomy of keys*, one ought
to bring specific and sound scientific logic argumentation.
Disseminating product information with wax of science is not the same
as science. It hurts both science and truth.

Please, Cimode. In Celkos text on the taxonomy of keys there is *not a
single* reference to a database product.

He does advertise his own work, but this doesn't bother me, just as
Bob Badours permanent swearing doesn't bother me much either.

As for the *content* of Celkos text and its relation(!) to database
theory (short of copying large parts of a book on this theme, I am
speaking colloquially here):

1. In the Relational Model, the key is part of the definition of a
relation (= table in practice). You don't have a relation if it
doesn't have a key.

I differ with the wording above. Here's an alternate wording: if you have
a relation, the tuples will be distinct, by definition. This means that the
entire tuple is either a candidate key or a super key. To discover
candidate keys, one merely needs to discover the constraints placed on the
data.



2. Theory never talks about *how* you obtain this key. It is just
assumed that it exists. It talks about candidate keys, primary
keys and other mathematical concepts that apply here.

OK, so theory never talks about this, but I will: data analysis.
Huh..But I thought that theory estalished predicates and true
propositions. How do you establish a proposition with such taxonomy
defined?

3. Celko classifies the kinds of keys that are used in practice.
Taxonomy is a science in its own right. His text is more of an
expose, it could easily be expanded to twenty pages or so. But his
conclusions nevertheless are valid and sound (a little bit expanded
by me):
Mmmm..I wander if confusing taxonomy is also a science...

I think this is a useful thinig to do, in the context that Joe originally
did it in.
Design practices, both best practices and others, sometimes elucidate
theory, sometimes not.
It's only when theory and alleged best practices contrdict each other that
further investigation is necessary. (remember, "Theory IS practical")
Hey I thought we were talking about external vs internal data/
reality. Damn, now you bring theory vs practice...(I will never
understand, I will never understand...)

;)
[Snipped]

.

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